Polymerization of olefins

ABSTRACT

A catalyst composition can be obtained by gently milling a milled mixture of magnesium chloride and a titanium tetrahalide with a magnesium alkoxide. The catalyst composition can be combined with a metallic hydride or, preferably, an organometallic co-catalyst, e.g., an organoaluminum compound, to form a catalyst useful for the polymerization of alpha-olefins.

This application is a continuation-in-part of our co-pending applicationSer. No. 003,439, filed Jan. 15, 1979 and now U.S. Pat. No. 4,240,929.

This invention relates to a process for polymerizing olefins. In anotheraspect, this invention relates to a catalyst composition for thepolymerization of alpha-olefins. In another aspect, this inventionrelates to a process for preparing a catalyst which can be used in analpha-olefin polymerization reaction. In another aspect, this inventionrelates to a catalyst composition which can be used in conjunction witha metallic hydride or organometallic co-catalyst to form a completecatalyst system useful in the polymerization of alpha-olefins. In yetanother aspect, this invention relates to a catalyst composition towhich a powdered diluent is added.

It is known to polymerize alpha-olefins and mixtures thereof accordingto the low pressure process of Ziegler. In this process, the catalystsused are prepared from mixtures of compounds of elements of Subgroups IVto VI of the Periodic Table and the organometallic compounds of theelements of Groups I to III of the Periodic Table. The polymerization isgenerally carried out in suspension, in solution or even in the gaseousphase.

Furthermore, processes using catalysts prepared by reacting a magnesiumalkoxide compound with a compound of an element of Groups IV to VI ofthe Periodic Table are known. For example, according to U.S. Pat. No.3,644,318, a compound of an element of Groups IV to VI of the PeriodicTable, e.g., titanium tetrachloride, is reacted with a magnesiumalkoxide to form a catalyst component. This catalyst component can thenbe mixed with an organoaluminum compound as co-catalyst.

The activity of an olefin polymerization catalyst is one importantfactor in a continuous search for the ultimate catalyst to be used in analpha-olefin polymerization reaction. The higher the activity andproductivity of the alpha-olefin polymerization catalyst, assuming theproperties and qualities of the polymer product remain the same, thegreater the favorability and acceptability of the catalyst for use inalpha-olefin polymerization reactions. Although catalysts that areprepared by reacting a magnesium alkoxide with a titanium compound havebeen found to be acceptable, improvements can be made.

It is an object of this invention, therefore, to provide an improvedprocess for the polymerization of olefins.

Another object of this invention is to provide a novel and improvedcatalyst for the polymerization of alpha-olefins.

Another object of this invention is to increase the polymer productionin an alpha-olefin polymerization process.

Still another object of this invention is to provide a catalyst ofincreased activity for the polymerization of alpha-olefins.

Other objects, aspects and the several advantages of this invention willbecome apparent to those skilled in the art upon the study of thisdisclosure and the appended claims.

SUMMARY OF THE INVENTION

The present invention provides a catalyst composition useful for thepolymerization of alpha-olefins. The catalyst composition is obtained bymixing a magnesium alkoxide with an intimate mixture of a magnesiumhalide compound and a tetravalent, halogenated titanium compound. Thecatalyst composition is then combined with an organometallic co-catalystto form a catalyst system useful in the polymerization of alpha-olefins.

In accordance with this invention a catalyst component for thepolymerization of alphaolefins is obtained by gently milling magnesiumalkoxide and a milled mixture of magnesium chloride and titaniumtetrahalide. It has been found that a surprisingly high polymerproductivity is obtained when the milled mixture of magnesium dichlorideand titanium tetrahalide is only gently milled with magnesium alkoxide.

Throughout this application the term "gently milling" is intended tomean a milling operation wherein the milled mixture of magnesiumchloride and titanium tetrahalide together with the magnesium alkoxideis placed into a receptacle together with grinding elements; thereceptacle is subjected to a moderate movement to cause tumbling ofthese grinding elements. The movement can be a movement of rotating,rocking or gently shaking the receptacle. The movement of the receptacleis such that only up to about 300 of the shaking, rocking or rotatingmovements occur per minute. Thus, as an example the receptacle may berotated at up to about 300 rpm, or specifically for instance at 150-200rpm. The grinding elements utilized can vary in shape as well as in thematerial from which they are made; examples for such grinding elementsinclude steel balls as well as zirconia cylinders.

One embodiment of this invention pertains to the formation of a catalystcomposition wherein an intimate magnesium halide-titanium compoundmixture is formed by milling and then milling the intimate mixture witha magnesium alkoxide. Many forms of milling can be used, however, it ispreferred that the magnesium alkoxide is rotary ball milled with theintimate magnesium halide-titanium compound mixture as a highly activecatalyst composition is thereby formed.

In another embodiment, the catalyst composition contains a powdereddiluent. The powdered diluent added to the composition can be polymerfines of polymers such as polyethylene, polypropylene, poly(arylenesulfide) and the like or refractory substances such as alumina, silica,chlorinated silica and the like. It is preferred to add the powdereddiluent to the catalyst composition when the magnesium alkoxide is addedto the magnesium halide-titanium compound mixture in order to eliminateor reduce caking that can occur during the subsequent milling operation.The preferred powdered diluents are poly(arylene sulfide) andchlorinated silica.

In another embodiment of the invention, the catalyst composition iscombined with an organometallic co-catalyst to form an active catalystsuitable for the polymerization of alpha-olefins such as ethylene. Theorganometallic co-catalyst can be selected from the organometalliccompounds that form with the metals of Groups IA, IIA or IIIA of thePeriodic Table, e.g., an organo-aluminum compound.

DETAILED DESCRIPTION OF THE INVENTION

The catalyst composition of this invention is obtained by mixing amagnesium alkoxide with an intimate mixture of a magnesium halidecompound and a tetravalent, halogenated titanium compound. The catalystsystem, when used in combination with an organometallic compound, suchas an organoaluminum compound, has been shown to be active forpolymerizing olefins into normally solid polymers which can befabricated into such useful articles as fibers, film, molded objects andthe like.

The catalyst systems of this invention are especially active for theproduction of ethylene homopolymers or copolymers containing up to about20 mole percent comonomer, the comonomer being selected from aliphatic1-olefins containing from 3 to 10 carbon atoms per molecule. Thecatalyst system is useful in the polymerization of alpha-olefins,especially for the polymerization of alpha-olefins such as ethylene.

Any suitable magnesium alkoxide can be employed for the purpose offorming the catalyst composition of this invention as there is norestriction on the hydrocarbyl groups outside of practicalconsiderations, e.g., ease of preparation and availability. Exemplarymagnesium alkoxides can be expressed as Mg(OR)₂ in which R is an alkylgroup containing from 1 to 20 carbon atoms. Exemplary compounds includemagnesium methoxide, magnesium ethoxide, magnesium isopropoxide,magnesium 2-ethylhexyloxide, magnesium dodecyloxide, magnesiumeicosyloxide. Presently preferred compounds, because of readyavailability and relatively low cost, are magnesium methoxide andmagnesium ethoxide. The compounds can contain up to about 3 moles of thecorresponding alcohol per mole of compound.

Any suitable tetravalent, halogenated titanium compound can be used aslong as the titanium has one halogen attached thereto. Suitablecompounds can be represented by the formula TiX_(a) (OR')_(4-a) in whichX stands for bromine, chlorine or iodine or mixtures thereof, a is aninteger of 1 to 4 and R' is an alkyl, cycloalkyl, or aryl group andcombinations thereof, such as alkaryl, containing from 1 to about 20carbon atoms. Specific examples of suitable compounds include titaniumtetrachloride, titanium dibromodichloride, titanium iodotrichloride,n-butoxytrichlorotitanium, chlorotridodecyloxytitanium,bromotricyclohexyloxytitanium, diphenoxydichlorotitanium, and the like.

The most preferred tetravalent, halogenated titanium compounds are thetitanium tetrahalides which include TiBr₄, TiCl₄, TiI₄ and mixturesthereof. Presently preferred is TiCl₄ because of ready availability andrelatively low cost.

The magnesium halide compounds appropriate for the purposes of thisinvention are the magnesium dihalides with magnesium chloride being thepreferred compound. Magnesium chloride is generally employed in the formof a finely divided powder. It can be preactivated by a grinding stepalthough such preactivation is not considered generally necessary.

The molar ratio of the magnesium halide to the titanium compound canrange rather widely as long as the final catalyst is effective forpolymerization. However, a presently preferred molar ratio of magnesiumhalide to titanium compound is in the range of about 2:1 to 25:1 withthe most preferred molar ratios being in the range of about 3:1 to 15:1because catalyst activity is especially good in that range.

The molar ratio of titanium compound to magnesium alkoxide can rangefrom about 0.1:1 to 10:1 and more preferably from about 0.5:1 to 5:1since catalytic activity is especially high in that range.

The catalyst composition is prepared by first preparing an intimatemixture of the magnesium halide and tetravalent, halogenated titaniumcompound. The magnesium halide and titanium compound can be admixed inany convenient method that insures intimate dispersion of components.Preferably, admixing is performed under intensive milling conditionssuch as prevail in a ball mill, vibrating ball mill, tower mill and thelike. A typical mill employable is a vibratory ball mill such as aVibratom, manufactured by Siebtechnik GMBH.

The magnesium halide and titanium compound mixture is then mixed withthe magnesium alkoxide in any convenient fashion. Rotary ball milling isthe preferred method of treating the magnesium halide and titaniumcompound mixture with the magnesium alkoxide since less caking of themixture occurs than in a vibratory mill. By rotary ball milling it ismeant the conventional form of ball milling wherein a horizontal vesselpartly filled with balls, small cylinders, etc., is rotated at speedsranging from about 10-200 rpm.

Milling can be done in an inert, dry atmosphere such as nitrogen, argonand the like under subatmospheric, atmospheric or superatmosphericpressures. Cooling can be employed to avoid excessive temperatures beinggenerated such as about 65° C. (150° F.), which can adversely affectcatalyst performance. Milling times can range from about 5 to 200 hours.Vibratory milling typically requires a shorter time and rotary ballmilling typically takes a longer time.

It is within the scope of the invention to dilute the catalystcompositions with a powdered diluent. Said diluent can be polymer fines,e.g., polyethylene, polypropylene, poly(arylene sulfide) and the like orrefractory substances such as alumina, silica, chlorinated silica andthe like. The preferred powdered diluents are poly(arylene sulfide) andchlorinated silica. The powdered diluent is preferably added along withthe magnesium alkoxide to eliminate or reduce caking that can occurduring the subsequent milling operation. When catalyst dilution isemployed, a rotary ball mill or vibratory mill can be used to producethe final catalyst compositions. Such diluents have particle sizesranging from about 60 mesh to 400 mesh (250-37 microns) or finer.

The amount of diluent employed with the catalyst can vary rather widelyso long as a composite active for polymerization is obtained. Generally,the composite can contain from about 1 to 90 wt. % diluent.

The catalyst composition, component A, can then be combined with aco-catalyst, component B, to form a catalyst system useful for thepolymerization of olefins. Component B is a hydride or organometalliccompound wherein said metal is selected from an element of Groups IA,IIA and IIIA of the Periodic Table. In other words, component B can be ahydride of a metal selected from Group IA, IIA and IIIA or anorgano-compound of the metals. The preferred compound to be used ascomponent B is an organoaluminum compound which can be expressed asR"_(b) AlX_(3-b) in which R" is a hydrocarbon radical selected from suchgroups as alkyl, cycloalkyl, aryl, alkaryl, aralkyl, alkenyl and thelike containing from 1 to 20 carbon atoms per molecule, X is halogen orhydrogen and b is an integer of 1, 2 or 3. Exemplary compounds includetrimethylaluminum, triethylaluminum, dimethylaluminum chloride,n-propylaluminum diiodide, diisobutylaluminum hydride, didodecylaluminumbromide, trieicosyaluminum, tridodecylaluminum, tricyclohexylaluminum,triphenylaluminum, diethylaluminum chloride, ethylaluminum dibromide andthe like and mixtures thereof.

Any mono-1-olefin can be polymerized in the presence of the catalyst ofthe present invention with the preferred reactant being ethylene orethylene plus another higher aliphatic mono-1-olefin containing from3-10 carbon atoms. The mono-1-olefin, or mixture thereof, is polymerizedby contacting the catalyst system of this invention using any of thewell known methods, e.g., by contacting in solution, in suspension or ingaseous phase, at temperatures ranging from about 20°-200° C. andpressures ranging from about atmospheric to about 1000 psig (6.9 MPa g).The homopolymerization and copolymerization reactions can be conductedbatchwise or in continuous fashion by employing any known process.

It is convenient when polymerizing ethylene in a bench scale process,for example, to conduct the polymerization batchwise in a stirredreactor employing a dry hydrocarbon diluent inert in the process such asisobutane, n-heptane, methylcyclohexane, benzene, toluene and the like,at a reactor temperature of about 80° C. and a reactor pressure of about280 psig (1.9 MPa). Ethylene is admitted to the reactor as required tomaintain the desired pressure. Molecular weight control agents such ashydrogen can be employed in the reactor, as known in the art, to adjustthe molecular weight of the polymer.

When the selected polymerization time is reached the reaction can beterminated by discontinuing the flow of ethylene and comonomer, if used,venting unreacted monomer(s) and diluent and recovering the polymer. Therecovered product can be treated to deactivate or remove catalystresidues such as by an alcohol wash, can be stabilized by admixture withan antioxidant(s) and can be dried to remove residual solvent, ifpresent, as is known in the art. Generally, because such low amounts ofcatalyst residues are present in the polymer product it is not necessaryto remove them to avoid discoloration of the polymer or corrosion ofprocessing equipment. Thus, it is usually only necessary to stabilizethe polymer after recovery and dry it before it is further processedinto pellets and/or converted into the final shaped product.

The present invention will be better understood upon study of thefollowing examples. The following examples are set forth as illustrativeof this invention and are not meant to be restrictive in any way.

EXAMPLE 1

A series of magnesium dichloride-titanium tetrachloride mixtures wasprepared by individually charging a 1 liter spherical steel vessel undernitrogen with 100 g of the mixture and 2400 g of 3/8 inch (0.95 cm)steel balls. Vibratory ball milling was employed at ambient conditionsfor a period of time ranging from 16-24 hours. Each sample was recoveredthrough a restricted passage in the vessel opening which allowed passageonly of the milled product. Each sample was stored under nitrogen in adry box until further use. The mole ratio of MgCl₂ -TiCl₄ ranged from4.7:1 to 10.5:1 in the samples thus prepared.

Samples of the MgCl₂ -TiCl₄ mixtures of 10 g or 20 g were subsequentlyrotary ball milled with suitable quantities of the magnesium alkoxideand diluent, if employed, by charging the components in a nitrogenatmosphere to a 0.24 liter ceramic vessel containing from 300-400 g ofcylindrical zirconia grinding media of 1/2×1/2 inches (1.3×1.3 cm)dimensions. Each sample was mixed by rotating at ambient temperature for24 hours at about 140 RPM. The products were recovered by passagethrough an 8 mesh screen and stored in a dry box under nitrogen untilready for testing as ethylene polymerization catalysts. The exact moleratios and/or weight ratios of the components employed are detailed insubsequent examples.

EXAMPLE 2

A 3.8 liter, stirred, stainless steel reactor was employed for ethylenepolymerization. The reactor was readied for each run by charging 3liters of dry n-heptane to it, closing the port, and heating reactor andcontents at 175° C. for 30 minutes. The reactor was drained and residualheptane purged with dry nitrogen. The reactor was then closed and cooledunder nitrogen pressure.

The prepared reactor was purged with dry isobutane vapor and 3 ml of theco-catalyst solution of 15 wt % triethylaluminum in dry n-heptane (2.8mmoles) was added followed by the catalyst. The reactor was closed, 2liters of dry isobutane charged, the reactor and contents were heated to80° C. and 100 psi (0.69 MPa) ethylene pressure added.

After a one hour polymerization run, the reaction was terminated byflashing the ethylene and isobutane from the reactor. The polymer wasthen recovered and weighed to obtain the yield.

Each polymer yield was divided by the weight of catalyst employed todetermine the calculated productivity expressed as kg polyethylene per gcatalyst per hour. When the catalyst contains a diluent, the calculatedproductivity is based on kg polymer per g diluted catalyst as well as kgpolymer per g catalyst contained in the diluted catalyst.

The quantities of catalyst components employed, mole ratios used andresults obtained are presented in Table I.

                                      TABLE I                                     __________________________________________________________________________    ETHYLENE POLYMERIZATION WITH MgCl.sub.4.Mg(OCH.sub.3).sub.2 CATALYSTS         CATALYST                         Calculated                                          Cal-     CALCULATED       Productivities                                      culated  MOLE RATIOS Polymer                                                                            kg polymer/g                                 Run                                                                              Weight                                                                            mmoles                                                                             Wt %                                                                              MgCl.sub.2                                                                        TiCl.sub.4                                                                         Al Yield                                                                              catalyst/hr                                  No.                                                                              mg  Ti   Ti  TiCl.sub.4                                                                        Mg(OR).sub.2                                                                       Ti g    Initial.sup.(a)                                                                    Final                                   __________________________________________________________________________    1  11.3                                                                              0.018                                                                              7.6 4.3 2.9  155                                                                              416  10.2 36.8                                    2  5.7 0.0087                                                                             7.3 "   1.4  322                                                                              235  "    41.2                                    3  9.4 0.013                                                                              6.7 :    0.72                                                                              215                                                                              202  "    21.5                                    4  10.6                                                                              0.014                                                                              6.3 5.8 4.7  200                                                                              373  14.2 35.2                                    5  15.9                                                                              0.021                                                                              6.2 "   2.3  133                                                                              596  "    37.5                                    6  7.7 0.0098                                                                             6.1 "   1.6  286                                                                              409  "    68.3                                    7  2.9 0.0037                                                                             "   "   "    730                                                                              198  "    68.3                                    8  16.0.sup.(b)                                                                      0.0034                                                                              6.1.sup.(c)                                                                      "   "    823                                                                              202  "      12.6.sup.(d)                          9  8.0 0.0099                                                                             5.9 "   1.2  283                                                                              362  "    45.2                                    10 9.9 0.012                                                                              7.6 "   "    233                                                                              434  "    43.8                                    11 2.0 0.0032                                                                             7.3 10.5                                                                              2.0  875                                                                               78  19.0 39.0                                    12 4.5 0.0069                                                                             6.7 "   1.6  406                                                                              203  "    45.1                                    13 3.3 0.0046   "   1.2  609                                                                              185  "    56.1                                    __________________________________________________________________________     Notes:-                                                                       .sup.(a) Before admixing Mg(OR).sub.2 with MgCl.sub.2.Ticl.sub.4 catalyst     .sup.(b) Catalyst weight excluding polyethylene diluent is 2.7 mg.            calculated.                                                                   .sup.(c) Based only on catalytic component.                                   .sup.(d) Based on catalyst only (excluding diluent), catalyst productivit     is calculated to be 74.8 kg polymer per g catalyst. Diluent is                polyethylene fines dried under nitrogen at 80° C. for 24 hours.        Particle size is less than 60 mesh (250 microns or less).                

                                      TABLE II                                    __________________________________________________________________________    EFFECT OF ALKOXIDE ON CATALYST COMPOSITION                                    CATALYST                                                                             CALCULATED        CALCULATED MOLE RATIOS                                      Diluent                         Polymer                                                                            CALCULATED PRODUCTIVITIES         Run                                                                              Total                                                                             Free wt. %                                                                             mmoles                                                                             wt %                                                                              MgCl.sub.2                                                                        TiCl.sub.4                                                                         Al   Yield                                                                              kg polymer/g catalyst/hr          No.                                                                              mg  mg   cat.                                                                              Ti   Ti  TiCl.sub.4                                                                        Mg(OR).sub.2                                                                       Ti   g    Initial.sup.(e)                                                                     Undiluted                                                                           Diluted.sup.(f)       __________________________________________________________________________    14.sup.(a)                                                                       13.3                                                                              13.3 100 0.017                                                                              6.0 5.8 2.0  165  487  16    36.6  --                    15.sup.(a)                                                                       17.8                                                                              3.6   20 0.0045                                                                             "   "   "    622  184  "     51.1  10.3                  16.sup.(a)                                                                       10.2                                                                              10.2 100 0.013                                                                              6.1 "   2.7  215  372  "     36.5  --                    17.sup.(a)                                                                       24.7                                                                              4.9   20 0.0062                                                                             "   "   "    452  228  "     46.5   9.2                  18.sup.(a)                                                                       12.0                                                                              2.4   20 0.0030                                                                             6.2 "   3.3  933  132  "     55.0  11.0                  19.sup.(a)                                                                       9.3 1.9   20 0.0025                                                                             6.3 "   4.0  1120  89  "     46.8   9.6                  20.sup.(b)                                                                       9.1 9.1  100 0.012                                                                              6.1 "   2.0  233  224  "     24.6  --                    21.sup.(b)                                                                       12.9                                                                              12.9 "   0.017                                                                              6.3 "   3.3  165  282  "     21.9  --                    22.sup.(b)                                                                       11.5                                                                              11.5 "   0.015                                                                              6.3 "   4.0  187  313  "     27.2  --                    23.sup.(c)                                                                       5.7 5.7  "   0.0076                                                                             6.4 5.2 2.0  368  214  13    37.5  --                    24.sup.(d)                                                                       8.0 8.0  "   0.0099                                                                             5.9 5.8 1.2  283  362  14    45.2  --                    25.sup.(d)                                                                       4.9 4.9  "   0.012                                                                              "   "   "    233  434  "     43.8  --                    __________________________________________________________________________     Notes:-                                                                       .sup.(a) Mg(OR).sub.2 is Mg(OC.sub.2 H.sub.5).sub.2, commercial sample.       .sup.(b) Mg(OR).sub.2 is Mg(OCH.sub.3).sub.2, commercial sample.              .sup.(c) Mg(OR).sub.2 is Mg(OCH.sub.3).sub.2.(CH.sub.3 OH).sub.1.7,           experimental preparation.                                                     .sup.(d) Mg(OR).sub.2 is Mg(OCH.sub.3).sub.2, experimental preparation.       .sup.(e) Before admixing (Mg(OR).sub.2 with MgCl.sub.2.TiCl.sub.4             catalyst.                                                                     .sup.(f) Polyethylene fines, see footnote d, Table I, for description.   

                                      TABLE III                                   __________________________________________________________________________    EFFECT OF DILUENTS ON CATALYST ACTIVITY                                                CATALYST                                                                         CALCULATED        CALCULATED MOLE RATIOS                                                                         CALCULATED                              To-                                                                              Diluent                       Polymer                                                                            PRODUCTIVITIES                 Run      tal                                                                              Free wt %                                                                              mmoles                                                                             wt %                                                                              MgCl.sub.2                                                                        TiCl.sub.4                                                                         Al Yield                                                                              kg polymer/g catalyst/hr       No.                                                                              Diluent                                                                             mg mg   cat.                                                                              Ti   Ti  TiCl.sub.4                                                                        Mg(OR).sub.2                                                                       Ti g    Initial.sup.(e)                                                                    Undiluted                                                                           Diluted             __________________________________________________________________________    26 PPS.sup.(a)                                                                         10.9                                                                             3.8  34.6                                                                              0.0048                                                                             6.1 5.8 2.0   583                                                                             317  16.1 83.4  29.0                27 "     4.6                                                                              1.5  "   0.0019                                                                             "   "   "    1470                                                                             381  "    254..sup.(b)                                                                        82.8                28 "     3.8                                                                              1.3  34.2                                                                              0.0017                                                                             6.3 "   2.9  1650                                                                             144  "    73.1  25.0                29 "     3.9                                                                              1.3  34.0                                                                              0.0017                                                                             "   "   3.9  "  141  "    108.  36.2                30 "     2.6                                                                              0.9  "   0.0012                                                                             "   "   "    2330                                                                             128  "    142.  49.2                31 "     9.1                                                                              3.1  "   0.0041                                                                             "   "    683 277                                                                              "    89.4 30.4                      32 Cl--Sio.sub.2.sup.(c)                                                               10.1                                                                             3.4  34.2                                                                              0.0045                                                                             "   "   2.9   622                                                                             255  "    75.0  25.2                33 "     3.6                                                                              1.2  34.7                                                                              0.0016                                                                             "   "   3.8  1750                                                                             124  "    103.  34.4                34 "     3.0                                                                              1.0  "   0.0013                                                                             6.1 "   2.9  2150                                                                             104  "    104.  34.7                35 "     4.2                                                                              1.4  34.4                                                                              0.0018                                                                             6.2 "   3.9  1550                                                                             154  "    110.  36.7                36 SiO.sub.2.sup.(d)                                                                   10.2                                                                             6.6  34.2                                                                              0.0087                                                                             6.3 "   2.9   322                                                                             285  "    43.2  14.8                37 "     14.6                                                                             5.1  34.7                                                                              0.0065                                                                             6.1 "   "     431                                                                             188  "    36.9  12.9                __________________________________________________________________________     .sup.(a) Polyphenylene sulfide, U.S. Pat. No. 3,354,129. Unscreened,          particle range from about 20 to less than 325 mesh (840 to less than 40       microns), about 74 wt % are 40-80 mesh. Dried under nitrogen for 24 hours     at 80° C.                                                              .sup.(b) Three hour polymerization run.                                       .sup.(c) Chlorinated microspheroidal silica, dried in chlorine ambient at     400° C. for 30 minutes. Particle sizes ranged from about 60 to les     than 325 mesh (250 to less than 40 microns), about 61 wt % ranges from        about 80-200 mesh. Material used unscreened.                                  .sup.(d) Silicatitantia cogel containing about 2.5 wt % Ti, calcined in       air at 870° C. and cooled to ambient temperature under dry             nitrogen. Particle size distribution similar to silica of footnote            .sup.(c). Material used unscreened.                                           .sup.(e) Before admixing Mg(OR).sub.2 with MgCl.sub.2.TiCl.sub.4 catalyst                                                                              

The results in Table I show that MgCl₂ TiCl₄ catalysts of various moleratios are significantly improved in ethylene polymerization activity bythe addition of magnesium methoxide as described in this invention.Improvement is noted over the entire MgCl₂ to TiCl₄ mole ratio range of4.3:1 to 10.5 to 1, and a ratio of 5.8:1 appears to be especiallydesirable. Run 8 results show that dilution of an invention catalystwith finely divided polyethylene also increases its activity even more.

Based on calculated productivity data obtained, the results show theinvention catalyst containing no diluents are capable of producingpolyethylene from about 1.1 to 4.8 times the quantities produced by thecontrol catalysts containing no added magnesium methoxide.

The results presented in Table II in runs 14-19 show that magnesiumethoxide can be substituted for the methoxide to give catalystcomposites quite active in ethylene polymerization. Run 24 demonstratesthat magnesium methoxide containing 1.7 moles methanol per mole alkoxideis about as effective as the alcohol-free alkoxide in preparing theinvention catalysts.

The enhanced activity imparted the invention catalysts by dilution withpolyethylene fines is directly brought out in the results shown in runs14 and 15 and in runs 16 and 17. Without a diluent calculated catalystproductivity is about 36.5 kg polymer per g catalyst. With a diluentcalculated catalyst activity based on the Mg(OR)₂ -promoted MgCl₂.TiCl₄contained in the diluted catalyst reaches about 51 kg polymer per gcatalyst in run 15 and 46.5 kg polymer per g catalyst in run 17.

The results shown in Table III demonstrate the effectiveness of severaltypes of diluent for use with the invention catalysts. Particularly goodresults are shown with polyphenylene sulfide and chlorinatedmicrospheroidal silica, e.g., calculated productivities ranging from75-142 kg polymer per g catalyst. A silica-titania cogel is shown to beless effective than the chlorinated silica, possibly because the surfacehydroxyl groups affect catalyst activity and do not permit the enhancedactivity to develop as with the other diluents.

EXAMPLE 3

A series of catalysts was prepared to compare those made according tothis invention with those prepared in other ways or outside the scope ofthis invention. For convenience the catalysts are described as follows:

A. Invention catalysts: These are described in Example 1 with thepolymerization results given in Table 1, runs 6, 7, 8. The catalysts aremade by vibratory ball milling MgCl₂ -TiCl₄ to obtain a composite whichis subsequently rotary ball milled with Mg(OR)₂ to produce the catalyst.

B. Invention catalysts prepared in an alternate but less preferablemanner by vibratory ball milling the Mg(OR)₂ with a vibratory ballmilled MgCl₂ -TiCl₄ composite: Each catalyst sample was prepared byvibratory ball milling the specified quantity of Mg(OR)₂ with thespecified quantities of other components in a 1 liter, sphericalstainless steel vessel containing about 2400 g of 0.95 cm diameter steelballs for 16 hours. The products were recovered as previously described.The amounts of components used are given in Table B.

                                      TABLE B                                     __________________________________________________________________________                                    Mole Ratio                                    Run                                                                              Grams Components     Mg(OCH.sub.3).sub.2.                                                                  TiCl.sub.4                                    No.                                                                              MgCl.sub.2.TiCl.sub.4.sup.(a)                                                          Diluent.sup.(b)                                                                    Mg(OCH.sub.3).sub.2                                                                  (MeOH)1.7                                                                             Mg(OR).sub.2                                  __________________________________________________________________________    B1 45       45   2.6    0       2.0                                           B2 45       45   2.2    0       2.4                                           B3 45       45   1.9    0       2.8                                           B4 80       0    0      7.6     2.0                                           B5 80       0    0      6.3     2.4                                           __________________________________________________________________________     .sup.(a) MgCl.sub.2 /TiCl.sub.4 mole ratio is 5.8:1                           .sup.(b) See footnote .sup.(d) of Table III.                             

C. Control catalysts prepared from vibratory ball milling of MgCl₂ withTiCl₄ : The specified quantities of each component were charged to a 1liter, spherical steel vessel containing about 2400 g of steel balls andmilled the specified time on a vibratory mill. The products wererecovered as previously described. The amounts of components used, sizeballs employed and milling times are listed in Table C.

                  TABLE C                                                         ______________________________________                                        Run  Ball Size                                                                              Milling Time                                                                             Grams      Mole Ratio                                No.  cm       hrs        MgCl.sub.2                                                                           TiCl.sub.4                                                                          MgCl.sub.2 /TiCl.sub.4                  ______________________________________                                        C1   1.3      40         90.0   12.1  14.8:1                                  C2   1.3      16         84.0   15.5  10.7:1                                  C3   0.95     24         84.1   15.9  10.5:1                                  C4   0.95     48         84.1   15.9  10.5:1                                  ______________________________________                                    

D. Control catalysts prepared from Mg(OR)₂ and TiCl₄ by contacting ahydrocarbon-Mg(OR)₂ slurry with TiCl₄ :

Control catalyst D1 was prepared by refluxing 5 g of Mg(OCH₃)₂(MeOH)₀.5, slurried in about 150 ml of dry n-hexane contained in a 500ml flask, with 51.8 g of TiCl₄ for 4 hours (about 65° C.) whilestirring. Stirring was discontinued, the mixture was cooled to roomtemperature, liquid decanted and the slurry was washed 3 times with 475ml portions of fresh n-hexane. The product was dried at room temperaturein a vacuum oven. The calculated molar ratio of TiCl₄ to Mg(OCH₃)₂ is5.5:1. (The actual amount of TiCl₄ retained was not determined.)

Control catalyst D2 was prepared by reacting a ball milled Mg.MgCl₂composite (containing 2 g Mg) with 7.9 g methyl alcohol(1.5×stoichiometric) in the presence of about 200 ml dry n-hexane atreflux for 1 hour. The mixture was refluxed an additional 4 hours whilestirring and then cooled to room temperature. Then to the stirredmixture was added 86.3 g of TiCl₄ and about 100 ml of n-hexane and themixture was refluxed for 4 hours, the stirring discontinued and themixture was cooled to room temperature. The liquid was decanted and theproduct was washed 5 times with 450 ml portions of n-hexane. The washedproduct was dried at room temperature in a vacuum oven. The calculatedmolar ratio of TiCl₄ to Mg(OCH₃)₂ is 5.4:1. (Actual TiCl₄ retained notdetermined.)

The catalysts were subsequently employed in the polymerization ofethylene in the manner described in Example 2. The details and resultsobtained are presented in Table D.

                                      TABLE D                                     __________________________________________________________________________    Catalyst                                                                               Calculated                                                                    Diluent        Calculated Mole Ratios                                                                      Polymer                                 Catalyst                                                                           Total                                                                             Free mmoles                                                                             Wt. %                                                                              MgCl.sub.2                                                                        TiCl.sub.4                                                                          Al  Yield Calculated Productivities         No.  mg  mg   Ti   Ti   TiCl.sub.4                                                                        Mg(OR).sub.2                                                                        Ti  g     kg polymer/g                                                                               Remarkst/hr          __________________________________________________________________________    A1   7.7 7.7  0.0098                                                                             6.1  5.8 1.6   286 409   53.1         invention            A2   2.9 2.9  0.0037                                                                             6.1  5.8 1.6   730 198   68.3         "                    A3   16.0.sup.(a)                                                                      2.7  0.0034                                                                             6.1.sup.(b)                                                                        5.8 1.6   823 202   74.8.sup.(c) "                    B1   13.8.sup.(g)                                                                      7.1  0.0023                                                                             3.2  5.8 2.0   1220                                                                              197   27.7.sup.(d) "                    B2   9.3.sup.(g)                                                                       4.8  0.0016                                                                             3.2  5.8 2.4   1750                                                                              118   24.6.sup.(e) "                    B3   16.5.sup.(g)                                                                      8.4  0.0028                                                                             3.2  5.8 2.8   1000                                                                              251   29.9.sup.(f) "                    B4   3.9 3.9  0.0012                                                                             5.9  5.8 2.0   2330                                                                              202   51.8         "                    B5   5.6 5.6  0.0018                                                                             6.0  5.8 2.4   1560                                                                              190   33.9         "                    C1   16.3                                                                              16.3 0.0102                                                                             3.0  14.8                                                                              na    275 349   21.4         control              C2   10.9                                                                              10.9 0.0090                                                                             3.9  10.7                                                                              na    311 216   19.8         "                    C3   14.8                                                                              14.8 0.0124                                                                             4.0  10.5                                                                              na    226 340   22.9         "                    C4   20.2                                                                              20.2 0.0169                                                                             4.0  10.5                                                                              na    166 440   21.8         "                    D1   14.6                                                                              14.6 nd   nd   nd  nd    nd  272   18.6         "                    D2   23.5                                                                              23.5 nd   nd   nd  nd    nd  252   10.7         "                    __________________________________________________________________________     Notes:-                                                                       Results for catalysts A1, A2, A3 are repeated from Table I, runs 6,7,8,       respectively.                                                                 na means not applicable                                                       nd means not determined                                                       .sup.(a) Includes polyethylene diluent, see footnote .sup.(d) of Table        .sup.(b) Based only on catalytic                                              .sup.(c) Calculated productivity is 12.6 kg polymer per g catalyst plus       diluent                                                                       .sup.(d) Calculated productivity is 14.3 kg polymer per g catalyst plus       diluent                                                                       .sup.(e) Calculated productivity is 12.7 kg polymer per g catalyst            .sup.(f) Calculated productivity is 15.2 kg polymer per g catalyst            .sup.(g) Includes silica diluent, see footnote .sup.(d) of Table III, als     Table B                                                                  

Inspection of the data presented in Table D reveals that catalysts madeaccording to the preferred mode of preparation (catalysts A1, A2, A3)exhibit good activity in polymerizing ethylene. That is, the bestresults are obtained when an MgCl₂.TiCl₄ composite is prepared byvibratory ball milling and that composite is subsequently admixed withMg(OR)₂ by employing rotary ball milling.

An alternate but less preferred method of producing the catalysts isshown by the B catalysts where the MgCl₂.TiCl₄ composite is subsequentlyadmixed with Mg(OR)₂ by employing vibratory ball milling. This system ofmixing components appears to give erratic results which can be as goodas the preferred process, e.g., polymerization results with A1 catalystand B4 catalyst are similar but with B5 an unexpected drop inproductivity occurs. However, the results with B5 catalyst are stillsubstantially better than those obtained with control catalysts C1-C4and D1, D2.

The substantially poorer polymerization results obtained with the Ccontrol catalysts consisting of MgCl₂ and TiCl₄ compared to theinvention catalysts containing Mg(OR)₂ points out the unexpectedbeneficial nature of the combination including MgCl₂ and Mg(OR)₂. Thisaspect is also shown in Table 1 where initial and final calculatedproductivities for the catalysts are disclosed.

The relatively poor polymerization results obtained with the D1 catalystconsisting only of Mg(OR)₂ and TiCl₄ indicates again that superiorcatalysts are made only when TiCl₄, MgCl₂ and Mg(OR)₂ are combined. (TheD catalysts were not analyzed, hence the amount of TiCl₄ present incombination with Mg(OR)₂ is unknown.) Furthermore, the results obtainedwith the D2 catalysts show that the specific manner of combining thetitanium compound, magnesium halide and magnesium alkoxide can make asignificant difference in catalyst activity.

EXAMPLE IV

In the following example, comparative runs were carried out to determinethe effect of the nature of the milling utilized in the preparation ofthe first catalyst component.

Vibratory Ball Milling

The vibratory ball milling was carried out in a 225 mL vessel using thequantities of reagents shown in the following table. The vibratory ballmilling was carried out in the presence of 14 stainless steel ballshaving a diameter of 13 mm.

Rotary Milling

The rotary milling in the second step of the present invention wascarried out in a 240 mL vessel with 16 cyclindric zirconia rods having adiameter of 13 mm and a length of 13 mm.

The total milling time in all instances was 16 hours. In the case ofruns 1, 2 and 4, the runs where the milling was carried out in twosteps, the first step was a four-hour milling whereas the second stepwas a twelve-hour milling.

The catalyst component obtained in the four runs was used forpolymerizing ethylene, employing 3 cc of a solution of 15%triethylaluminum in heptane as the cocatalyst. The polymerization wascarried out at 80° C. for one hour with a partial pressure of ethyleneof 100 psi (0.69 MPa). For further details, reference is made to example2 of this patent application. The other quantities utilized in thepreparation of the catalyst as well as the productivity of polyethyleneare shown in the following table. In run 1, the milled mixture ofmagnesium chloride and titanium tetrachloride was removed from themilling vessel and charged to a porcelain vessel. Not the total quantityof 6.76 grams but only 5.47 grams of the complex was recovered andtherefore the quantity of magnesium ethoxide utilized was smaller in run1 as well. Since the weight ratio of the complex and the magnesiumalkoxide utilized was, however, the same in all four runs and since theproductivity is related to one gram of catalyst the results of theseruns are fully comparable.

                                      TABLE IV                                    __________________________________________________________________________       (a) (b) (c)  (d)                                                           __________________________________________________________________________               MgCl.sub.2                                                                    TiCl.sub.4                                                         Run                                                                              MgCl.sub.2                                                                        TiCl.sub.4                                                                        Complex                                                                            Mg(OEt).sub.2   Productivity                                  No.                                                                              (g) (g) (g)  (g)   Procedure g/gcat/hr                                     __________________________________________________________________________    1  5.5 1.26                                                                              5.47 0.98  (1)vib. ball mill                                                             (a) + (b) → (c)                                                        (4 hr)    14,928                                                              (2)then gently mill                                                           (c) + (d) (12 hr)                                       2  5.5 1.26                                                                              6.76 1.21  (1)vib. ball mill                                                             (a) + (b) → (c)                                                        (4 hr)    4,100                                                               (2)add (d), continue                                                          vib. ball milling                                                             (12 hr)                                                 3  5.5 1.26                                                                              6.76 1.21  (1)vib. ball mill                                                                       5,000                                                               (a), (b), (d)                                                                 (16 hr)                                                 4  5.5 1.26                                                                              6.76 1.21  (1)vib. ball mill                                                                       9,008                                                               (a) + (d) → (e)                                                        (4 hr)                                                                        add (b), continue                                                             vib. ball milling                                                             (12 hr)                                                 __________________________________________________________________________

The above results show that the process of this invention involving agentle milling of a milled mixture of magnesium chloride and titaniumtetrahalide with magnesium alkoxide (run 1) results in a surprisinglyincreased productivity compared with both processes in which the secondmilling step is a vibratory ball milling step (run 2) and processes inwhich the three ingredients are vibratory ball milled together in a onestep milling operation (run 3). Furthermore, the inventive process alsoresults in a far superior productivity than achieved by first vibratoryball milling magnesium chloride and magnesium ethoxide and thenvibratory ball milling the so-obtained mixture with titaniumtetrachloride (run 4).

Reasonable variations and modifications which will become apparent tothose skilled in the art can be made in the present invention withoutdeparting from the spirit and scope thereof.

We claim:
 1. A catalyst composition obtained by gently milling amagnesium alkoxide with a milled mixture of a magnesium halide compoundand a titanium tetrahalide said gently milling being characterized by upto about 300 shaking, rocking or rotating movements per minute of areceptacle containing grinding elements, said magnesium alkoxide andsaid milled mixture.
 2. A catalyst composition in accordance with claim1 wherein the magnesium alkoxide is rotary ball milled with the milledmixture.
 3. A catalyst composition in accordance with claim 1 wherein apowdered diluent is added to the composition.
 4. A catalyst compositionin accordance with claim 3 wherein said powdered diluent has a particlesize of no greater than about 250 microns.
 5. A catalyst composition inaccordance with claim 3 wherein said powdered diluent is polyarylenesulfide.
 6. A catalyst composition in accordance with claim 1 whereinthe molar ratio of the magnesium halide to the titanium tetrahalide isin the range of about 2:1 to about 25:1 and the molar ratio of titaniumtetrahalide to magnesium alkoxide is in the range of about 0.1:1 toabout 10:1.
 7. A catalyst composition in accordance with claim 5 whereinthe molar ratio of the magnesium chloride to the titanium tetrahalide isin the range of about 3:1 to about 15:1 and the molar ratio of titaniumtetrahalide to magnesium alkoxide is in the range of about 0.5:1 toabout 5:1.
 8. A method for preparing a catalyst composition comprisingpreparing a milled mixture of magnesium chloride and a titaniumtetrachloride, and then gently milling the mixture with a magnesiumalkoxide said gently milling being characterized by up to about 300shaking, rocking or rotating movements per minute of a receptaclecontaining grinding elements, said magnesium alkoxide and said milledmixture.
 9. A method in accordance with claim 8 wherein said milledmixture is rotary ball milled with the magnesium alkoxide.
 10. A methodin accordance with claim 8 wherein the milling times are in the range ofabout 5 to about 200 hours.
 11. A method in accordance with claim 10wherein a powdered diluent is added to the composition subjected to saidgently milling operation.
 12. A method in accordance with claim 11wherein said powdered diluent is added to the composition along with themagnesium alkoxide.
 13. A method in accordance with claim 12 wherein thepowdered diluent added to the compositions is poly(arylene sulfide). 14.A catalyst for the polymerization and copolymerization of olefinscomprising two components A and B wherein:component A is obtained bygently milling magnesium alkoxide with a milled mixture of a magnesiumchloride and a titanium tetrahalide said gently milling beingcharacterized by up to about 300 shaking, rocking or rotating movementsper minute of a receptacle containing grinding elements, said magnesiumalkoxide and said milled mixture, and component B is a metallic hydrideor organometallic compound wherein said metal is selected from anelement of Groups IA, IIA and IIIA of the Periodic Table.
 15. A catalystin accordance with claim 14 wherein the magnesium alkoxide is rotaryball milled with said milled mixture.
 16. A catalyst composition inaccordance with claim 14 wherein a powdered diluent is added to thecomposition subjected to said gently milling operation.
 17. A catalystin accordance with claim 16 wherein said powdered diluent has a particlesize of no greater than about 250 microns.
 18. A catalyst in accordancewith claim 16 wherein said powdered diluent is poly(arylene sulfide).19. A catalyst in accordance with claim 18 wherein said titaniumtetrahalide is titanium tetrachloride.
 20. A catalyst in accordance withclaim 18 wherein component B is an organoaluminum compound.
 21. Acatalyst in accordance with claim 20 wherein the organoaluminum compoundis selected from the group consisting of trimethylaluminum,triethylaluminum, tridodecylaluminum, tricyclohexylaluminum,triphenylaluminum, diethylaluminum chloride, diisobutylaluminum hydrideand ethylaluminum dibromide.
 22. A catalyst in accordance with claim 18wherein the molar ratio of the magnesium chloride to the titaniumtetrahalide is in the range of about 2:1 to about 25:1 and the molarratio of titanium tetrahalide to magnesium alkoxide is in the range ofabout 0.1:1 to about 10:1.
 23. A catalyst in accordance with claim 22wherein the molar ratio of the magnesium chloride to the titaniumtetrahalide is in the range of about 3:1 to about 15:1 and the molarratio of titanium tetrahalide compound to magnesium alkoxide is in therange of about 0.5:1 to about 5:1.
 24. A method for the preparation of acatalyst which comprises:forming a component A by preparing an intimatemixture by milling a magnesium chloride and a titanium tetrahalide andthen gently milling said mixture with a magnesium alkoxide said gentlymilling being characterized by up to about 300 shaking, rocking orrotating movements per minute of a receptacle containing grindingelements, said magnesium alkoxide and said milled mixture, and thencombining component A with a component B which is a metallic hydride ororganometallic compound wherein said metal is selected from an elementof Groups IA, IIA and IIIA of the Periodic Table.
 25. A method inaccordance with claim 24 wherein the magnesium chloride and titaniumtetrahalide mixture is rotary ball milled with the magnesium alkoxide.26. A method in accordance with claim 24 wherein the milling times arein the range of about 5 to about 200 hours.
 27. A method in accordancewith claim 24 wherein powdered diluent is added to the composition. 28.A method in accordance with claim 27 wherein said powdered diluent isadded to the composition along with the magnesium alkoxide.
 29. A methodin accordance with claim 27 wherein the powdered diluent added to thecomposition is poly(arylene sulfide).
 30. A catalyst compositionobtained by milling a magnesium alkoxide with a milled mixture of amagnesium halide compound and a titanium tetrahalide, said milling ofmagnesium alkoxide with said milled mixture being carried out byrotating a milling vessel at speeds ranging from about 10 to 200 rpm.